DiscussionTools' reply widget might default to visual mode when the user has completely disabled visual editor for articles. It should behave the same as if the user has chosen "Always give me the source editor" in preferences and default to source mode. (See T250523.)

It seems that if you disable the visual editor, we stop updating the data about which editor you used the last time you edited, but we still remember which editor you used previously. If that was the visual editor, then it seems that the reply widget will also use visual mode initially.

Steps to reproduce:

1. Create a new account
2. Open a page for editing (e.g. https://en.wikipedia.org/w/index.php?title=The_Fighting_Temeraire&action=edit)
3. Switch to the visual editor
4. Leave the editor
5. Go to https://en.wikipedia.org/wiki/Special:Preferences
6. Check "Editing → Temporarily disable the visual editor while it is in beta" and save changes
7. Go to a discussion page with reply links, e.g. https://en.wikipedia.org/wiki/Wikipedia:Main_Page/Errors?dtenable=1
8. Click a reply link

Expected: reply widget opens in source mode.
Actual: it opens in visual mode.

Originally reported here: https://www.mediawiki.org/wiki/Topic:Vpmbb9wrfgd5e0id